1. Field of the Invention
The present invention relates to contact lenses and, more particularly, to contact lenses that changes or enhances a color of a first area of the eye, e.g., the iris, without altering a second area of the eye, e.g., the pupil.
2. Description of the Prior Art
Eyes are perceived to be particularly attractive when the color of the iris is vibrant or sparkling. Hydrogels modified to diffract light have significant potential to create sparkle and vibrancy. U.S. Pat. No. 7,059,719 (hereinafter “the '719 patent”), which is incorporated herein by reference, discloses a colored contact lens that incorporates a crystalline colloidal ordered array of particles to diffract light to impart vivid sparkling color to the whole lens or a portion of the lens. When worn, an embodiment of the cosmetic lens disclosed in the '719 patent generally restricts color modification to the iris of the eye, excluding generally the area of the pupil of the eye. However, diffracting hydrogels including polymerized crystalline colloidal (PCCA) arrays have not been used for this purpose as the art does not disclose a method or means to make a contact lens that restricts the diffracting hydrogel to areas of desired color modification.
It is believed that restricting such diffracting hydrogels to only certain areas of the contact lens corresponding to eye structure may be difficult to achieve due to the usual method employed to manufacture the contact lens which usually involves a molding process.
U.S. Pat. No. 5,281,370 (hereinafter “the '370 patent”) and U.S. Pat. No. 5,989,923 (hereinafter “the '923 patent”) disclose hydrogels that are capable of Bragg diffraction that produces vivid colors in the visible spectrum. The '370 patent and the '923 patent are both incorporated herein by reference. The '370 patent discloses a self-order array of particles whose spacing is on the order of the wavelength of visible light. The '923 patent discloses a holographic pattern capable of diffracting visible light.
The '719 patent (discussed above) discloses colored contact lenses that obtain their color through Bragg diffraction. The '719 patent further discloses that all or part of the lens may be colored. Diffraction is produced by inclusion of hydrogels that diffract visible light. The '719 patent, however, does not disclose a means or method to localize the diffractive material in the lens so that the color effect is isolated to a specific area of the eye.
Generally cosmetic lenses are produced by placing a monomer, cross linker and initiator mixture in a mold and exposing the thus contained mixture to an energy source such as visible light, UV light or heat depending on the initiator. To tint such a lens, a tint can be added to the mixture prior to polymerization (see e.g., U.S. Pat. No. 6,123,845). The tint diffuses throughout the mixture such that the entire resultant lens is tinted. The tint then appears over both the iris and the pupil of the eye. The tint typically does not produce vibrant color modification so that the effect to pupil is generally unnoticed. However, if the entire lens were a diffractive hydrogel material that produces vivid colors, the pupil would be strongly colored, giving the eye a strange or unnatural appearance.
If the mixture used to synthesize the diffractive hydrogel were just placed into the lens monomer mixture, they would both mix and the diffractive properties might be changed or lost altogether. If the diffractive properties remained, both the iris and pupil would experience an undesirable color change.
To illustrate, consider the synthesis of a polymerized crystalline colloidal array (PCCA) hydrogel. Synthesis of the PCCA hydrogel requires mixing a monomer, a cross-linker, an initiator to facilitate polymerization, and like-charged nanometer sized spherical particles in a water-based solution. The mixture cannot contain radicals which are removed, e.g., without limitation, with an ion exchange resin, so that the charged spherical particles can self-organize into an ordered array. The mixture is then polymerized using heat, visible light, or ultraviolet (UV) light, depending upon the material used to synthesize the colloidal particles and, subsequently, the initiator. Thus, the PCCA monomer mixture cannot just be added to the lens monomer as it would disperse throughout the lens monomer.
What is, therefore, needed is a structure, means and method to manufacture a contact lens that uses a diffracting hydrogel to (1) modify only the color of a desired area of the eye, e.g., the iris of the eye, when the lens is worn or (2) modify the wavelength of light received/reflected in a desired area of the eye, e.g., the pupil of the eye.